What is felt?
Felt is classed as a non-woven. Simply put, it's just a tangled mass of fibres, http://en.wikipedia.org/wiki/Felt, traditionally wool, but these days it can be made of more-or-less any fibre, and it has multiple uses.
The two ways of making felt are: 1) wet felting; a hand made process requiring the application of moisture and friction to wool to cause the fibres to mat together, and 2) needle felting; either by hand or machine. Special barbed needles are used to tangle the fibres together. The Bellacouche felt employs the needle felting method and takes place at a local mill.